I've run 7 marathons (PR 3:29) and 4 half- marathons (PR 1:34) and this Dec. my goal is 3:15 (BQ for male 35-39). I currently run 40-45 mpw and will increase to 60mpw in June. But if I focus on breaking 1:30 for a half- marathon first, will that make it easier to break 3:15 for the full?
I rarely comment on training threads, but I will here because I have run a 3:16:04 and broken 1:30. In my opinion if you are in sub 1:30 shape you should be able to break 3:15. I didn't break 1:30 until another 5 months after my marathon and could probably have run ~1:31 when I ran the 3:16.
My opinion would be just train for the marathon. If you have an opportunity to jump in a half in your training it can be a good way to see where you are at.
I would say that being in shape for the 3:15 will make the 1:30 easier if that makes sense.
I had run about 1:33 before I ran a 3:15. I had a 1:30 before I ran 3:09.
So I should focus on the 3:15 and the abilty for a 1:30 will develop.